ABU GHRAIB, Iraq — Falah Hassan spent five years behind the walls of Abu Ghraib prison before he was freed in a mass pardon last fall. On Sunday, he strolled around what was once one of the world’s most feared prisons, playing guide to a visitor while looking for a power generator to loot.

“They tortured me every day in my first six months here. After that, it was a beating here, a beating there,” recalled Hassan, who said he got a 15-year jail term in 1998 for stealing a pair of trousers and a shirt off a laundry line.

Abu Ghraib, a sprawling compound 12 miles west of Baghdad, was considered one of the most potent symbols of Saddam Hussein’s regime, a source of tales of horror and despair.

Critics of Saddam’s regime have long told of the disappearances, torture and executions without trial that befell those suspected of plotting against the Iraqi leader or challenging his policies. Much of that allegedly took place in Abu Ghraib.

By the standards of the fallen regime, the punishment recalled by Hassan — nails in the back of his hands, beatings with wooden clubs and iron bars — was moderate.

Former inmates have told of chemical and biological weapons experiments on prisoners, and the execution of hundreds in the 1990s as part of a campaign by Saddam’s son, Qusai, to ease crowding.

Qassem As-Samawi, an Iraqi journalist who spent time at Abu Ghraib on espionage charges, told of tiny isolation cells where political detainees were kept for up to a year without seeing a single person.

“When we hear prisoners shout Allah Akbar (God is great), we know that someone is being executed,” said As-Samawi, who was released in 1991 more than two years into a seven-year sentence and later moved to Canada.

One of Abu Ghraib’s more storied inmates, physicist Hussein Shahrastani, was jailed in the 1980s when he refused to head an atomic bomb program. He escaped after the 1991 Gulf War and heads a human rights group in London.

The prison belongs to the Ministry of Social Affairs but was run by Saddam’s feared intelligence department. In 1996, Saddam fired the social affairs minister for telling a local newspaper that Abu Ghraib was overcrowded and new prisons were needed.

No one ever knew how many prisoners it held. But relatives and friends said that in the early 1990s, tens of thousands of people would gather outside each week to visit inmates.

“When I visited Hassan, they detained us for three, sometime four hours, until they counted every inmate as a precaution, and then we left,” said Mohammed Rasheed, one of Hassan’s friends.

It’s not clear when Abu Ghraib was emptied of its inmates. In October, a blanket pardon by Saddam sent home thousands, including Hassan, but it was never clear whether political detainees benefited from that amnesty.

Four foreign journalists arrested in Baghdad late last month were held in Abu Ghraib for a week. Newsday’s Matt McAllester said he and his colleagues “were aware of the screams of other prisoners, especially at night when they were taken out of their cells.” The four slept on concrete floors in 6-by-11-foot cells.

On Sunday, the only people in Abu Ghraib were Hassan, several of his cousins and a few of his friends. As two American helicopters hovered overhead, they searched for the elusive generator.

Images of Saddam and quotations from his speeches are slathered everywhere in the prison. “Let us build Iraq and may your enemies die of jealousy,” reads one. A large mural shows Saddam surrounded by soldiers, farmers, workers and women soldiers in chadors.

Hassan said jailers never gave him food while he was at Abu Ghraib. Only his mother’s weekly delivery of food kept him from going hungry, he said.

“Look at me now. I don’t know what happened to me,” said the gaunt 26-year-old laborer, his voice bitter as he described himself before prison — a healthy specimen who worked out and lifted weights.

“I have no appetite,” he said. “I just smoke.”

Hassan wasn’t having any luck finding his generator. But some things in the prison remained unlooted.

In the execution ward, two hanging ropes dangled from the ceiling. The metal arms that the executioner yanked to open iron doors under the condemned stood at the ready.

Executions took place Wednesdays, a day after families visited death-row inmates, Hassan said. “Their spirits visit me every night in nightmares,” he said.